Electrophoretic display sheet, electrophoretic display, electric apparatus, and method of manufacturing electrophoretic display sheet

ABSTRACT

An electrophoretic display sheet, includes: a substrate; and an electrophoretic layer made into a film on the substrate, including a plurality of microcapsules, in which an electrophoretic disperse medium containing at least one kind of electrophoretic particle is sealed, and a binder coupling the microcapsules to one another, wherein a degree of affinity of the substrate, the microcapsule, and the binder is respectively formed such as to increase in order of the microcapsule, the binder and the substrate.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to an electrophoretic display, which makes use ofmovement of charged molecules in an electric field for displayinginformation, and its manufacturing process.

2. Related Art

Broadly speaking, an electrophoretic display is constituted by anelectrophoretic layer provided between a pixel electrode substrate and acommon electrode substrate. The electrophoretic layer includes more thanone kind of colored electrophoretic particle and a liquid phase dispersemedium, which makes the electrophoretic particle movable, and is sealedbetween the both substrates. Aid when a pixel signal (voltage)corresponding to two-dimensional image information is applied betweeneach pixel electrode of the pixel electrode substrate and the commonelectrode substrate, a position of the electrophoretic particle is setcorresponding to a level of the pixel signal, whereby an image isformed.

As referenced above, the electrophoretic particles move in the dispersemedium, while if the electrophoretic display tilts, uneven distribution(unbalanced) of the electrophoretic particles can occur. To preventthis, the electrophoretic layer is divided by partition members or aplurality of electrophoretic particles and the disperse medium arewrapped in a wall member and made into microcapsules. For example, U.S.Pat. No. 5,961,804 shows an example in which the electrophoretic layerof the electrophoretic display is formed by micro-encapsulation.

U.S. Pat. No. 5,961,804 is an example of related art.

In a case where the electrophoretic layer is formed bymicro-encapsulation, to form an intricate image, the microcapsules needto be compactly coated all over the substrate without a gap such that afilm needs to be made without a gap while microcapsules are tightly incontact with one another.

However, in a currently available technique of forming theelectrophoretic layer through the microcapsules, a liquid in which themicrocapsules are dispersed is coated on the substrate and dried, thusmaking it easy to produce gaps among the microcapsules. It is difficultto adjust concentration of the microcapsules in the disperse liquid aswell as coating work so as to prevent such phenomenon.

Now, it may be conceived to coat the disperse liquid in advance, so thatthe electrophoretic layer becomes a thick film in advance, while this isheld between two electrode substrates to push the microcapsule layerinside, thereby sticking one microcapsule to another very closely.However, such arrangement causes residual stress (restoring force) togenerate inside the microcapsule layer, and exfoliation and deformationtend to occur between the electrophoretic layer and the electrodesubstrate. In case of a large-sized substrate, overall pressuring(holding) itself is difficult to be applied. Further, if the disperseliquid solidifies, deformation is difficult to occur, hence, before thedisperse liquid dries up, the electrode substrates need to be gluedtogether.

SUMMARY

An advantage of the invention is to provide an electrophoretic displaysheet and an electrophoretic display which enable an electrophoreticlayer, in which microcapsules adhere closely together, to be formed onan electrode substrate to provide for intricate image display.

A further advantage of the invention is to provide a manufacturingprocess of an electrophoretic display sheet and an electrophoreticdisplay which enable an electrophoretic layer, in which themicrocapsules adhere closely together, to be formed more easily on theelectrode substrate.

According to a first aspect of the invention, an electrophoretic displaysheet of the invention includes: a substrate; and an electrophoreticlayer made into a film on the substrate, including a plurality ofmicrocapsules, in which an electrophoretic disperse medium containing atleast one kind of electrophoretic particle is sealed, and a binderbonding or fixing the microcapsules to one another, wherein a degree ofaffinity of the substrate, the microcapsule, and the binder isrespectively formed such as to increase in order of the microcapsule,the binder and the substrate.

At this point, the electrophoretic display sheet is that which is madeup of an electrophoretic layer formed on the substrate. Further, theaffinity is determined by an angle of contact between the substrate anda reference liquid, the angle of contact between the microcapsule andthe reference liquid, and the angle of contact between the binder andthe reference liquid. The reference liquid is, for example, water, butnot limited to this, and a selection can be made as appropriate.

According to such constitution, when the binder entwined around themicrocapsules attempt to spread along the substrate, it operates toextend the microcapsules at a broader width along the substrate. As eachmicrocapsule spreads on the substrate, adhesion among the microcapsulesbecomes tighter, thereby making it possible to obtain an electrophoreticdisplay sheet having an electrophoretic layer without a gap between onemicrocapsule and another. This enables an electrophoretic displaycapable of forming intricate imagery to be obtained.

According to a second aspect of the invention, the electrophoreticdisplay sheet includes a substrate; and an electrophoretic layer madeinto a film on the substrate, including a plurality of microcapsules,each of the plurality of microcapsules including an electrophoreticdisperse medium and at least one kind of electrophoretic particle, and abinder bonding the microcapsules to one another, wherein the affinitybetween the binder and the substrate and the affinity between the binderand the microcapsule are set to be higher than the affinity between themicrocapsule and the substrates.

Even in such constitution, when the affinitive binder entwined aroundthe microcapsules attempt to spread along the substrate, it operates toextend the microcapsules at a broader width along the substrate. As eachmicrocapsule spreads on the substrate, adhesion among the microcapsulesbecomes tighter, thereby making it possible to obtain an electrophoreticdisplay sheet having an electrophoretic layer without a gap between onemicrocapsule and another. This enables an electrophoretic displaycapable of forming intricate imagery to be obtained.

Preferably, the electrophoretic layer has a planar structure with onemicrocapsule tightly adhering to another due to the affinity of thebinder. This makes it possible to obtain an electrophoretic displaysheet having an electrophoretic layer with the microcapsules tightlyadhering to one another without a gap.

Preferably, the binder includes, for example, a water-soluble resin.This makes it possible, for example, for the affinity between the wallmember of the water-soluble microcapsule and the binder to improvesignificantly, so that when the binder attempts to spread over thesubstrate, the microcapsules also spread because of wettability of thebinder and are fixed on the substrate.

Preferably, the wall member of the microcapsule includes a water-solubleresin. This enables the affinity among the microcapsule, for example,the binder including the water-soluble resin and the substrate toimprove significantly. When the binder attempts to spread on thesubstrate, the microcapsules also spread due to surface tension of thebinder and are fixed on the substrate.

Further, an electrophoretic display according to the invention includes:a first and a second substrates which are placed mutually opposite toeach other, and on each opposite surface of which electrodes arerespectively formed; and an electrophoretic layer made into a film onthe first substrate, including a plurality of microcapsules, in which anelectrophoretic disperse medium containing at least one kind ofelectrophoretic particle is sealed, and a binder bonding themicrocapsules to one another, wherein a degree of affinity of the firstsubstrate, the microcapsule, and the binder is respectively formed suchas to increase in the order of the microcapsule, the binder and thefirst substrate.

According to such constitution, when the binder entwined around themicrocapsules attempt to spread along the first substrate, it operatesto extend the microcapsules at a broader width along the substrate. Aseach microcapsule spreads on the first substrate, adhesion among themicrocapsules becomes tighter, thereby making it possible to obtain anelectrophoretic display layer with the microcapsules packed with no gapbetween one microcapsule and another. As a result, an electrophoreticdisplay capable of forming intricate imagery can be obtained.

According to a third aspect of the invention, a manufacturing process ofan electrophoretic display of the invention includes: coating, on asubstrate which is a first angle of contact relating to a referenceliquid, a mixture of a plurality of microcapsules which is a secondangle of contact relating to the reference liquid, and the binder whichis a third angle of contact relating to the reference liquid; and dryingthe substrate coated with the mixture and forming an electrophoreticlayer including the plurality of microcapsules, wherein a relationshipof θ3>θ2>θ1 holds where the first angle of contact is θ1, the secondangle of contact is θ2, and the third angle of contact is θ3.

Preferably, applying lyophilic processing to the substrate prior tocoating the mixture is included.

Preferably, applying lyophilic processing includes plasma processing andozone processing.

Through such constitution, it is possible to form an electrophoreticlayer in which the microcapsules adhere closely together. Anelectrophoretic display sheet (electrophoretic display) of high contrastby curbing uneven display can be obtained. Further, since no externalpressure is applied to between the substrates as in the currentlyavailable technique, residual stress of the microcapsules (or restoringforce) contributes to not generating exfoliation and distortion betweenthe substrates.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers refer to like elements.

FIG. 1 is a longitudinal section showing an embodiment anelectrophoretic display according to the invention.

FIG. 2 presents schedule drawings to explain a manufacturing process ofan electrophoretic display shown in FIG. 1.

FIG. 3 presents explanatory diagrams to explain operations in anembodiment of an electrophoretic display according to the invention.

FIG. 4 is an explanatory diagram to explain a state of anelectrophoretic layer of an electrophoretic display according to theinvention.

FIG. 5 is an explanatory diagram to explain characteristics (angle ofcontact) of materials in a manufacturing process of an electrophoreticdisplay according to the invention.

FIG. 6 presents diagrams to show examples of electronic equipment towhich an electrophoretic display of the invention is applicable.

FIG. 7 presents diagrams to show examples of electronic equipment towhich an electrophoretic display of the invention is applicable.

FIG. 8 is a longitudinal section of an electrophoretic display as acomparison example.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the invention will be described as follows with referenceto the drawings.

Electrophoretic Display Sheet and Electrophoretic Display

FIG. 1 is a longitudinal section of an embodiment of an electrophoreticdisplay according to the invention.

In this working example, a common electrode substrate 10 as a substrateand an electrophoretic layer 30 formed thereon constitute anelectrophoretic display sheet. However, the electrophoretic layer 30 maybe formed on a pixel electrode substrate 20, and these may be used as anelectrophoretic display sheet. In this case, the same result can beobtained even if the common electrode substrate 10 is replaced by thepixel electrode substrate 20.

An electrophoretic display 1 consists of the common electrode substrate10 which formed a common electrode 12 on a substrate 11, anelectrophoretic layer 30 which is formed by utilizing surface tension ofa binder 36, as explained later, on microcapsules 35 includingelectrophoretic particles 31, a plurality of drive elements, which arerespectively driving a plurality of pixel electrodes arrayed in a matrixpattern on the substrate 21 and each pixel, and a pixel electrodesubstrate 20 constituted by forming a pixel electrode circuit 22including a plurality of wiring and the like.

The common electrode substrate 10 and the pixel electrode substrate 20are placed opposite to each other in a manner of sandwiching theelectrophoretic layer 30. In this working example, since themicrocapsules 35 of the electrophoretic layer 30 are packed without agap in a stone wall shape or a tile shape as expeditiously as possible,for example, the affinity of the microcapsule 35, the binder 36, and thecommon electrode substrate 10 is controlled (or set).

For example, when water is set as a reference liquid for measuring theaffinity of each material and each substrate, the microcapsule 35, thebinder 36, and the common electrode substrate 10 have respectiveaffinity to water. Further, each material and each substrate areselected so that a degree of affinity to water increases in order of themicrocapsule 35, the binder 36, and the common electrode substrate 10.

Or materials and substrates are selected so that the affinity betweenthe binder 36 and the common electrode substrate 10 and the affinitybetween the binder 36 and the microcapsule 36 become larger than theaffinity between the microcapsule 35 and the common electrode substrate10.

Large affinity herein means a small difference of an angle of contactrelating to the reference liquid. For example, when there is a largelyophilic property of the substrate and the microcapsule 35 (in thestrict sense of the word, a wall member 33 which is a constituentelement of the microcapsule 35), it means a small difference (A−B)between the angle of contact (A) of water to the substrate and the angleof contact (B) of water to the wall member 33.

Further, when there is a large lyophilic property between themicrocapsule 35 and the binder 36, it means a small difference betweenthe angle of contact of water to the wall member 33 and the angle ofcontact of water to the binder 36.

The common electrode substrate 10 forms a common electrode 12 in a layeron the substrate 11.

A pixel electrode substrate 20 forms in a layer, on the substrate 21, apixel electrode circuit layer 22 which includes pixel electrodes in amatrix pattern corresponding to a number of pixels and active elements.

It is preferable that the pixel and part of the wiring of the pixelelectrode circuit layer 22 are a transparent electrode film such as ITOand that a drive element is an active element such as a thin filmtransistor (TFT).

Substrates 11 and 21 employed for the electrode substrate have, as a rawmaterial, a plastic material in a sheet shape, such as glass orpolyethylene terephthalate (PET). Further, its thickness (average) isset as appropriate depending on respective components and usage, andthere is no particular limitation. For example, in a case where asubstrate having flexibility is to be used, its thickness is preferablyon the order of 20 to 500 μm, and more preferably, on the order of 25 to250 μm. This makes it possible to proceed with miniaturizing theelectrophoretic display 1 (especially, making into a thin type) whilemaintaining harmony between flexibility and strength.

For the common electrode 12, that which has transparency of light withITO, ZnO and the like as its material, preferably, what is virtuallytransparent (colorless and transparent, colored transparent orsemitransparent) is acceptable. This enables status of anelectrophoretic particle 31 in an electrophoretic disperse liquid 32 tobe explained later, that is, information (image) displayed in theelectrophoretic display 1 to be easily recognizable through visualexamination.

Further, its thickness (average) is set as appropriate depending oncomponents, usage, and the like. There is no particular limitation. Butpreferably it is on the order of 0.05 to 10 μm, more preferably on theorder of 0.05 to 5 μm.

With respect to the common electrode substrate 10, to secure affinitywith the binder 36 and the microcapsule 35 (wall member 33) to beexplained later, lyophilic processing such as plasma irradiation andozone irradiation is suitable. Note that if the substrate has theaffinity originally desired, it is not particularly necessary to applylyophilic processing.

The electrophoretic layer 30 is a single layer (not overlaying in athickness direction but one by one) in which a plurality ofmicrocapsules 35 are arrayed in a row vertically and horizontallywithout mutual gaps through the binder 36, and it is made into a film onthe common electrode substrate 10. This enables the electrophoreticdisplay 1 to exhibit better display performance.

This microcapsule 35 is constituted by wrapping the electrophoreticdisperse liquid 34 with the wall member 33. As the component of the wallmember 33, for example, that which has the water-soluble characteristiccan be used. Take, for instance, a compound of gum arabic and gelatin aswell as various resin materials such as a urethane resin and a melamineresin. Of these, one kind or a combination of more than two kinds can beused.

It is preferable for such microcapsules 35 to have an approximatelyuniform size. This enables the electrophoretic display 1 to have uniformquality of display and to exhibit better display performance.

The electrophoretic disperse liquid 34 is obtained by dispersing(suspension) with a dispersing method such as stirring at least one kindof electrophoretic particle 31 with a liquid disperse medium 32.

So long as electrophoretic particle 31 has a property of electrificationand is a molecule which is electrophoretic in the liquid phase dispersemedium 32 through action of the electric field, there is no speciallimitation. Pigment molecules such as titanium oxide, resin moleculessuch as an acrylic resin, or at least one kind of these compoundmolecules may be suitably used.

An average particle size (diameter of average particle in volume) of theelectrophoretic particle 31 is preferably on the order of 0.1 to 10 μm.If the average particle size of the electrophoretic particle 31 is toosmall, a sufficient contrast ratio cannot be obtained mainly in avisible light region. As a result, it is considered that a displaycontrast of the electrophoretic display 1 may drop.

On the other hand, if the average particle size of the electrophoreticparticle 31 is too large, depending on factors such as its kind, ittends to precipitate, so that deterioration of display quality of theelectrophoretic display 1 may be considered.

As the liquid phase disperse medium 32, that which has comparativelyhigh insulating property such as dodecyl benzene is suitably used.

Further, as necessary, a disperse and charge control agent such as atitanium type coupling agent and an aluminum type coupling agent may beadded into the liquid phase disperse medium 32 (electrophoretic disperseliquid 34).

Still further, as necessary, various dyes such as an anthraquinone dyeand an azo dye may be dissolved in the liquid phase disperse medium 32.

Of resin materials excelling in affinity with the common electrodesubstrate 10 and the capsule wall member 33 (microcapsule 35) andexcelling in insulating property, for example, one kind or a combinationof more than two kinds of water-soluble high molecule materials such aspolyvinyl alcohol and cationic cellulose may be suitably used.

In the working example, there is shown an embodiment which is a film ofthe electrophoretic layer 30 made on the common electrode substrate 10.The film may be made on the pixel electrode substrate 20, and in thatcase, lyphilic processing is applied onto the pixel electrode substrate20.

In the constitution referenced above, when a voltage is impressedbetween the pixel electrode circuit layer 22 (of a pixel electrode) andthe common electrode 12, an electric field generates therebetween. Thiselectric field causes the electrophoretic particle 31 to move inside themicrocapsule 35 and an image is displayed.

In forming the electrophoretic layer 30 as referenced above, theaffinity among the microcapsule 35, the binder 36, and the commonelectrode substrate 10 are utilized as explained later. Accordingly, bymeans of the surface tension of the binder 36, each microcapsule 35 isdeformed into the common electrode substrate 10 side and film-makingfree from any gap is made between one microcapsule to another. Themicrocapsule layer is fixed on the common electrode substrate 10 by thebinder 36.

Consequently, without pressuring between the substrates and distortingthe microcapsules 35 like the currently available technique, and alsowithout being concerned about quality deterioration such as exfoliationof the common electrode substrate 10 and uneven display due to residualstress (or restoring force) of the microcapsules 35, it is possible toobtain, through a simpler manufacturing process, the electrophoreticdisplay 1 which provides high image quality.

FIG. 4 schematically shows an example (plan view) of a state of themicrocapsules 35 of the electrophoretic layer 30 in the working exampleas viewed from above. It is seen that the microcapsules 35 are mutuallyformed in the shape of the stone walls or the tiles with very few gapsamong the microcapsules.

FIG. 8 shows a comparison example. Elements in this figure correspondingto elements in FIG. 1 are given like numbers and description of suchelements is omitted.

In the comparison examples, the electrophoretic layer is simply coatedon one of the two substrates 10 and 20, and a structure is such as tosandwich it with two substrates. Consequently, there is a gap betweenone microcapsule 35 to another.

By comparison to the electrophoretic display of this comparison example,according to the constitution of the working example, a film is madewhile the microcapsules 35 forming the electrophoretic layer are beingpacked with no gaps among themselves, hence, no uneven display qualityis produced thus to enable high resolution image display to be made.

Further, in the comparison example, if an attempt should be made toarray the microcapsules tightly without a gap by changing the shape ofthe microcapsules as in this working example, it is necessary topressure externally the substrates themselves, which sandwich theelectrophoretic layer 30 including the microcapsules, so as to deformthe microcapsules. However, that is not necessary in this workingexample, so there are no chances such as substrate exfoliation anddeformation due to residual stress of the microcapsules which couldgenerate in case of pressuring, and high resolution image display can bestably obtained.

Manufacturing Process

FIG. 2 is a presentation with scheduling drawings of a manufacturingprocess of the electrophoretic display (electrophoretic display sheet)shown in FIG. 1.

First, as shown in FIG. 2A, in process A, the common electrode 12 isformed on the substrate 11 and the common electrode substrate 10 ismanufactured. After the formation, lyophilic processing is applied to asubstrate surface of an electrode side of the common electrode substrate10. For lyophilic processing, plasma irradiation, ozone irradiation andthe like are suitable. By carrying out such processing, an electrodesurface of ITO and the like of the substrate surface is activated, thusimproving wettability.

Next, as shown in FIG. 2B, in process B, a mixture of premixedmicrocapsules 35 and the binder 36 is coated on the common electrodesubstrate 10 (to be more specific, on the common electrode 12) so thatthere is uniform coating.

As a coating method, a doctor blade method, a spin coat method and thelike are suitable. As referenced above, the microcapsule 35, the binder36, and the common electrode substrate 10 have respective affinity.Further, the material and the substrate are selected or formed such thatthe degree of affinity may increase in the order of the microcapsule 35,the binder 36, and the common electrode substrate 10.

As shown in FIG. 2C, in process C, the mixture of the microcapsules 35and the binder 26 uniformly coated in process B is dried for about 10minutes at a temperature of 90° C., and the microcapsules 35 are madeinto a film without gap on the common electrode substrate 10 through thebinder 36 and fixed.

FIG. 3 are explanatory diagrams to explain operation when themicrocapsules 35 are made into a film on the common electrode substrate10. FIG. 3A shows a state where the mixture of microcapsules 35 and thebinder 36 is coated on the common electrode substrate 10. As referencedabove, the microcapsule 35, the binder 36, and the common electrodesubstrate 10 have respective affinity and are formed so that the degreeof affinity increases in the order of the microcapsule 35, the binder36, and the common electrode substrate 10.

Or the affinity between the binder 36 and the common electrode substrate10 and the affinity between the binder 36 and the microcapsule 35 areset to be higher than the affinity between the microcapsule 35 and thecommon electrode substrate 10.

For example, when water is set as the reference liquid, it is set upsuch that a relationship θ3>θ2>θ1 holds where the angle of contactbetween the common electrode substrate 10 subjected to lyophilicprocessing and water is θ1, the angle of contact between the material ofthe binder 36 and water is θ2, and the angle of contact between thematerial of the microcapsule 35 and water is θ3.

At this point, as shown in the explanatory diagram of FIG. 5, the angleof contact θ is an angle formed by a tangential line drawn from a pointof contact between the liquid and a solid into a perpendicular plane ofthe solid when the liquid is in contact with the solid surface. It isalso called a “wet angle.” In case of being wettable, the angle ofcontact becomes an acute angle, while in case of being not wettable, theangle of contact becomes an obtuse angle.

In the working example, for example, there are θ1=3.5° in regard to thesubstrate after ozone irradiation, θ2=47° in regard to the binder whichused polyvinyl alcohol, and θ3=67° in regard to the wall member by thecompound material of gum arabic and gelatin. Note that the binder andthe wall member are measured when they are respectively in the filmstate.

As shown in FIG. 3B, under the conditions described above, as the binder36 entwined around the microcapsules 35 attempts to spread along thecommon electrode substrate 10, a surface tension of the binder 36 causesto expand the microcapsules 35 themselves (in the direction of arrow).Expanded microcapsules 35 are fixed on the common electrode substrate 10in a single layer (one by one without overlaying in the thicknessdirection) in the stone wall shape or the tile shape arrayed in a rowvertically and horizontally with no mutual gaps.

In this manner, the electrophoretic display sheet is manufactured.

As shown in FIG. 2D, in process D, an adhesive 41 for sticking the pixelelectrode substrate 20 arranged opposite to the common electrodesubstrate 10 is coated on the electrophoretic layer 30 which was madeinto a film. In coating the adhesive, it may be on the entire surface orperiphery of the electrophoretic layer 30, so long as the microcapsules35 are sealed with the pixel electrode substrate 20 and the commonelectrode substrate 10.

Finally, as shown in FIG. 2E, in process E, the pixel electrodesubstrate 20 made by a separate process is glued to the common electrodesubstrate 10 such that its electrode side surface joins the adhesive 41,thereby sealing and fixing the electrophoretic layer 30 which was madeinto a film. In this way, an electrophoretic display using theelectrophoretic display sheet is obtained.

FIG. 4 shows the electrophoretic layer 30 in the film state obtained asa result of process C. In this manner, by pressuring the oppositesubstrates, without pushing and expanding the microcapsules 35, when thebinder 36 entined around the microcapsules 35 spreads on the substrate,the microcapsules themselves expand due to the surface tension of thebinder 36. The electrophoretic layer 30 can be made into a film on thecommon electrode substrate 10 with the microcapsules 35 in the state ofbeing packed without a gap in the stone wall shape or the tile shape.

The electrophoretic display 1 as referenced above can be built intovarious electric apparatus. Electric apparatus according to theinvention equipped with the electrophoretic display will be described asfollows.

FIGS. 6 and 7 are diagrams showing examples of electronic equipment towhich the above-referenced electrophoretic display is applicable. FIG.6A is an example of application to a mobile phone. The mobile phone 230comprises an antenna part 231, a voice output unit 232, a voice inputunit 233, an operating unit 234, and the electrophoretic display 1 ofthe invention. In this way, the electrophoretic display according to theinvention can be used as a display.

FIG. 6B is an example of application to a portable electronic book, andan electronic book 250 consists of a dial operating part 251, apushbutton operating part 252, and the electrophoretic display 1according to the invention.

FIG. 7A is an example of application to a still image display, and astill image display 300 is provided with the electrophoretic display 1according to the invention. Note that the still image display accordingto the invention is likewise applicable to a monitor unit used in apersonal computer and the like.

FIG. 7B is an example of application to a roll-up type still imagedisplay, and the roll-up type still image display 310 has theelectrophoretic display according to the invention.

As described above, based on the illustrated embodiments, descriptionhas been made of the electrophoretic sheet, the electrophoretic display,the manufacturing process of the electrophoretic display, and theelectric apparatus using the electrophoretic display according to theinvention. While the invention is not limited to these working examples,the constitution of each part or unit can be replaced with anyconstitution having like functions. Further, any other constituentelement may be added to the invention.

Furthermore, the invention may be a combination of more than any twoconstitutions (characteristics) out of each embodiment referenced above.

1. An electrophoretic display sheet, comprising: a substrate; and anelectrophoretic layer formed on the substrate, the electrophoretic layerincluding a plurality of microcapsules and a binder, each of theplurality of microcapsules including at least an electrophoreticparticle and an electrophoretic dispersion medium, the binder bondingthe plurality of microcapsules each other, a first lyophilic property ofthe substrate being larger than a second lyophilic property of thebinder, the second lyophilic property of the binder being larger than athird lyophilic property of each of the microcapsules.
 2. Theelectrophoretic display sheet according to claim 1, the first lyophilicproperty being determined by a contact angle between the substrate and areference liquid, the second lyophilic property being determined by acontact angle between the binder and the reference liquid, and the thirdlyophilic property being determined by a contact angle between the eachof the microcapsules and the reference liquid.
 3. An electrophoreticdisplay sheet, comprising: a substrate; and an electrophoretic layerformed on the substrate, the electrophoretic layer including a pluralityof microcapsules and a binder, each of the plurality of microcapsulesincluding at least an electrophoretic particle and an electrophoreticdispersion medium, the binder bonding the plurality of microcapsuleseach other, an affinity between the substrate and the binder beinglarger than an affinity between the substrate and each of themicrocapsules, an affinity between the binder and each of themicrocapsules being larger than an affinity between the substrate andeach of the microcapsules.
 4. The electrophoretic display sheetaccording to claim 1, having a planar structure with one microcapsuletightly adhering to another due to the second lyophilic property of thebinder.
 5. The electrophoretic display sheet according to claim 1, thebinder including a water-soluble resin.
 6. The electrophoretic displaysheet according to claim 1, a wall member of the microcapsule includinga water-soluble resin.
 7. The electrophoretic display sheet according toclaim 1, the substrate being a pixel electrode substrate or a commonelectrode substrate.
 8. An electrophoretic display including theelectrophoretic display sheet according to claim
 1. 9. An electricapparatus having an image display provided with the electrophoreticdisplay according to claim 8.